Catalytic reaction processes for producing acrylic acid using glycerin as a starting material consist of a glycerin dehydration reaction as the first step, and a partial oxidation reaction of acrolein as the second step. Since the two reactions occur in the presence of a catalyst, the use of a catalyst is essential.
However, the activity of a catalyst, in particular, the activity of a catalyst for the glycerin dehydration reaction, gradually decreases as the reaction proceeds, and one of major causes of such a decrease in catalytic activity is the loss of catalytic active sites due to the deposition of coke-like carbon produced during the reaction. Reduction in the activity of the catalyst leads to a decrease in the yield of acrylic acid as the final product, and thus, in order to commercially produce acrylic acid using glycerin, it is necessary to maintain the catalytic activity as long as possible. However, the existing patents related to the reaction for producing acrylic acid using glycerin mainly focus on the catalytic activity and merely include results of experiments performed for a relatively short period of time under mild reaction conditions, and thus the content related to the life span of the catalyst has not been properly addressed.
Meanwhile, it is possible to maintain the life span of a catalyst for a long period of time by adding a specific component to the catalyst and changing the reaction conditions and thereby oxidizing coke-like carbon produced in the catalyst for the glycerin dehydration reaction during the reaction in real time. However, acrolein, which is the product, and acrylic acid, can also be oxidized and removed under the reaction condition by which the coke carbon is oxidized, and thus it is necessary to establish a composition of the catalyst capable of selectively removing coke carbon without significantly affecting the product and the reaction conditions suitable for the composition.